Food container having improved ventilation

ABSTRACT

A plastic food container for crisp or crunchy foods includes a lid adapted for sealing arrangement with a base. Exhaust vents are selectively disposed on the top surface of the container, such that when the container is closed, rising vapors in the container easily flow out of the container. The convection movement of rising hot vapors causes the induction of ambient air into the container through a first air intake port and a counterpart air intake port disposed between the two engaged rims. The first intake port and its counterpart allow inducted air to enter directly and horizontally into the container. One or more channels are formed in the floor of the base and are aligned with a line defined by the first intake port and its counterpart to allow for the cross flow of drier inducted air underneath the container&#39;s food contents.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/218,770, filed on Jun. 19, 2009. The content of that application isincorporated by reference herein in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

SEQUENCE LISTING, TABLE OR COMPUTER PROGRAM ON COMPACT DISC

Not applicable.

FIELD OF INVENTION

This invention relates generally to ventilated plastic food containers.The invention is more specifically related to disposable plastic foodcontainers designed to hold heated or freshly-cooked crisp, crunchy ortexture-sensitive foods that require significant amounts of humidityremoval.

BACKGROUND OF THE INVENTION

It is known to use disposable plastic containers in the food preparationand restaurant industry to package prepared or take-out foods. Thetypical food container of the prior art consists of a clear or solidcolor base and a clear lid. The clear lid of the prior art plastic foodcontainer allows visible inspection of the container contents. The lidand base of the prior art plastic food container may be separatearticles or may be hingedly attached to each other.

The lid and base of the prior art plastic container have complementaryinterlocking rim structures that seal the container. This interlockingrim arrangement is beneficial in preventing spillage of food contentsfrom the container. In addition, this interlocking rim arrangementpromotes heat build-up inside the container during microwaving andretains the temperature of hot foods placed in the container. When warmfoods are placed in a closed container, steam and condensation candevelop inside the container. This is particularly so when the containerwith warm food is placed into a storage area at room temperature orless. Steam and condensation may also form inside a container holdingfood when the container is stored in an environment where external heatis applied to it (for example through microwaving, heat plates, heatlamps, warming tunnels, etc.). The build up of condensation and steaminside the container can result in the over-moistening of the containedfood. This build up is particularly unwanted in the case of any food ofsensitive texture, especially crisp or crunchy foods. In addition,undesirable food moistening is exacerbated when condensation drips downonto the food contents. In extreme cases, the condensate may pool at thebottom of the container leaving desirably crisp foods (e.g., vegetables)or crunchy foods (e.g., fried chicken or fried seafood) unpalatablysoggy.

In the case of supermarket fried chicken (or seafood) for example, thesupermarket prepares the fried chicken in its deli department, resultingin a cooked food product having a temperature of about 190 degreesFahrenheit. After cooking, the hot fried chicken is placed into thecontainer. The container may be sold immediately. If not, the containercontaining the fried chicken is typically placed in a heated displayarea and made available for sale as a “hot” food item for up to 4 hours.In the prior art container, the heat from the hot chicken builds up inthe container and, in turn, causes moisture build-up in the container.As a consequence to this moisture build-up, the fried chicken's crispbattered coating becomes soggy.

The solution to preventing over-moistening of cooked food, however, isnot simply a case of providing unregulated venting. In the firstrespect, unregulated venting allows the food to dry out and over-harden.More importantly, in addition to palatability concerns, containers forcooked foods must address safety issues. If the container is vented toomuch, the temperature of the fried chicken can drop below the minimumtemperature required by health departments or good food servingpractice. These same concerns hold true for other establishments likerestaurants and with respect to other texture sensitive foods likeunbreaded cooked crab that can degrade if heat and moisture are notproperly removed from the container.

In order to maintain the crispness of food contents within a closedcontainer, it is known to provide the prior art food container withexhaust ventilation means. In this regard, the lid of the prior artplastic food container typically contains one or two surface vents inthe form of cruciate slits. The cruciate slits form near-circular tabsthat can be deformed upward to permit egress of steam formed inside thecontainer. The one or two slits are located on the surface of thecontainer lid, not in relation to other venting structures of thecontainer, but instead in a manner that detracts least from theaesthetic appeal of the container. Though these slits assist in theexhaust venting of steam gases from the container, moisture build-upinside the container still occurs.

In the case of microwavable storage containers (as opposed to deli casecontainers) manufacturers have chosen to deal with removal of moisturedamaging steam by constructing container rims whereby the lid rim canassume two different positions on the base rim. One position keeps thecontainer sealed. The other position allows exhaust venting. In the caseof these latter containers, the sealed lid assumes a second fixedexhaust venting position on the base either through manual repositioningor by the lifting action of rising pressure inside the container. Oncethe lid is in the fixed exhaust venting position, steam can escape thecontainer by flowing along and between the contour of the rim structuresand out through the container. The contour of these rim structures canrequire egressing steam to undergo flow restricting direction changes(including direction reversals). The drawback to these exhaust ventingsolutions is that they still result in the creation of interior vaporsand condensation in the container, particularly in the case of theself-activating lid Also, because air must flow around the contour ofrims, these containers promote only the egress of air out of thecontainer and do not allow drying air into the container.

U.S. Pat. No. 6,257,401 discloses a thermoplastic container for foodwith a cover that is removably attached to the base to define a foodstorage chamber. A downwardly extending rib formed in the cover rim isintermittently provided with a plurality of notches that are alignedwith respective notches formed in an upwardly extending elongated rib ofthe base. With the cover in place atop the base, the conjunction of thebase notches and the cover notches define apertures. However, as is bestshown in FIG. 11 of that patent, the notches of the lid rim and base rimare offset, such that air flow into the container is directed upwardtoward the upper apertures of the lid. Another set of apertures foradditional ventilation are provided in the side walls of the cover.

Because of the venting drawbacks of the prior art container with respectto desirably crisp or crunchy foods, container manufacturers havedesigned containers having textured surface grids on the container floorthat keep the food contents raised above pooled food juices orcondensate. These grids can create pooling areas that collect thecondensate and juices. The container of U.S. Pat. No. 6,257,401 includesa plurality of small wells in the container bottom, the function ofwhich is to purposefully retain food juices via capillary action orsurface tension. These solutions, however, do not completely remedy thecreation of food-damaging steam and fluids inside the container. Infact, they can make it worse. In particular, the condensate and juicesmay drip into and pool in the wells of the container's floor grid and beretained. This pooled liquid absorbs heat and creates rising steam thatinfuses the lower portion of the container's food contents with texturedamaging moisture.

There is thus a need in the art for a plastic food container thatreduces steam creation and enhances container venting to preventover-moistening of desirably crisp or crunchy foods.

SUMMARY OF THE INVENTION

The present invention satisfies the need in the art and provides anaesthetically appealing food container that is easy to use, whileproviding for improved moisture removal. In this respect the presentinvention container achieves balanced vapor removal by incorporatingstructures that enhance the exhaust venting of the container withstructures that allow for efficient air intake. The container usesconvection and guided flow of inducted air to prevent theover-moistening of food product.

The present invention comprises a plastic food container including a lidand a base. The lid and base each have a peripheral rim. The lid rim isadapted for sealing engagement with the base rim. When the container issealed with hot food contents, the heat load created by the food causesthe moisture laden air to rise and exit through selectively positionedand numbered exhaust vents in the top surface of the container lid. Inthis regard, the top surface exhaust vents are numbered and positionedin relation to the expected temperature and humidity of the container'scontents. The convection movement of warm moist air upwardly in thecontainer and through the top surface exhaust vents causes the inductionof air through the intra-rim intake ports hereinafter described.

It is a further feature of the present invention container that the lidrim and base rim when in closed engagement form at least one firstintake port disposed between the two rims. To achieve optimum balancedventing and eliminate humidity dead zones in the container, each firstintake port has a counterpart intake port disposed between the two rims.Additionally, the first intake port and its counterpart intake port areoriented such as to permit air to enter, directly and generallyhorizontally, into the container through them and not encounterobstructing rim structures or have to change directions or angles whiletraveling through the rims.

The first intake port and its counterpart intake port define a lineinside the container. The container's floor can have at least onechannel formed in it, which is aligned with the line defined by thefirst intake port and a counterpart intake port. By aligning the floorchannels with at least one intake port, a cross flow of inducted ambientair is allowed whereby the container promotes the flow of relativelydrier air under the container's food contents. This flow of air not onlyhelps evaporate collected condensate and food juices, it removes thevapor away from the underside of the food content, preventing itsdamaging absorption. The container floor may comprise channels alignedwith two or more sets of intake ports.

In more specific summary, the present invention plastic food containercomprises a lid adapted for sealing arrangement with a base. The lid hasa peripheral rim structure that complementarily engages the peripheralrim structure of the base. The base has a floor and a sidewall extendingbetween the floor and the rim. In contrast to prior art containersutilizing through-the-rim exhaust or intake venting, it is a feature ofthe present invention that when the lid is fully closed to the base, themating rim structures create at least two intake ports that allowgenerally horizontal and direct (unrestricted) flow of air into thecontainer through the closed rims. Preferably, each intake port islocated on the rim in opposing relationship to another intake port.Hence, each intake port is located such that it is across from anotherintake port on the other side of the container. The positioning of theintake ports allows for the cross-flow of air through the container.

In the preferred embodiment, the rim structure of the lid has a channelshaped to receive spaced apart projections on the base rim structure.When the lid is closed to the base, the channel of the lid rim structurereceives the projections on the base rim structure. The height of theprojections emanating from the base rim structure prevents the lidflange from sealing completely against the base flange. As a result,when the lid is fully engaged to the base, the spaces between the baserim projections create rim air intake ports.

The present invention container further comprises elevated (preferablyembossed) projecting ribs from the base floor. These ribs create one ormore channels on the container floor that compared to the prior art arespecifically aligned with a line defined by at least two intake portslocated within the engaging container rims. These ribs and channelsprovide for several beneficial effects. First, as in the case with thegrid or textured surface of the prior art container, the ribs keep thefood contents elevated from the base floor and away from collectingliquids. However, in combination with the intake ports, the alignedchannels act like baffles and allow for the free passage of gases andvapors underneath the food contents. Thus, should pooled liquids in thecontainer start steaming, the channels of the present inventioncontainer allow for the evacuation of steam out through the top surfaceexhaust vents in the lid instead of into the food. In addition, byvirtue of their alignment with the intake ports, the channels of thepresent invention container allow for the end-to-end cross flow ofmoisture-removing air underneath the container's food contents in theevent a pressure differential exists between the ends of the channels.This arrangement not only enhances the removal of pooled moisture, butalso aids in drying of the bottom of the food contents. Thus, theconvective movement of warm air inside the container causes induction ofair through the rim intake ports. That air, being relatively cooler thanthe existing vaporous air inside the container, drops to the floor ofthe container. This drop is effected, in part, by the generallyhorizontal (not upwardly angled) orientation of the rim intake ports.Once the cool, dry air reaches the container floor, it flows as guidedby the channels. Thus, the intake ports along with the aligned, one ormore channels allow the direct, unimpeded flow of relatively dry air toenter into the container from the intake ports and pass under the foodcontents. While passing under the food contents, heat is transferredfrom the food contents to the incoming air. That heated air rises,scavenging moisture from the existing air in the container as it rises.

To further enhance the convection flow in the container, the preferredembodiment container includes a plurality of exhaust vents disposedabout the top surface of the container lid and not along any of thelid's outermost side surfaces. This arrangement of top-surface-onlyvents removes the dead-air effect caused by having apertures on the sideof the lid in close proximity to the rim intake ports. By removing thisdead-air effect, convection in the container is enhanced. In addition,by removing the vents from the extreme side of the lid by the intakeports, rising air in the container does not intercept the inducted airfrom the intake ports and push it out of the container.

While the invention is susceptible to various modifications andalternative forms, a specific embodiment thereof has been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that it is not intended to limit theinvention to the particular forms disclosed. Quite to the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred embodiment of the presentinvention container in the open arrangement.

FIG. 2 is a perspective view of a preferred embodiment of the presentinvention container in the closed arrangement.

FIG. 3 is a plan view of the present invention container in the openarrangement.

FIG. 4 is a cross-section view taken along line A-A of FIG. 3.

FIG. 5 is a side elevation view of the preferred embodiment presentinvention container in the closed arrangement.

FIG. 6 is a perspective view of the inside of the base of the preferredembodiment present invention container.

FIG. 7 is a perspective view of the inside of the lid of the preferredembodiment present invention container.

FIG. 8 is a side elevation view of the lid of the preferred embodimentpresent invention container.

FIG. 9 is a side elevation view of the base of the preferred embodimentpresent invention container.

FIG. 10 is an enlarged view of detail area Z of FIG. 4.

FIG. 11 is an enlarged view of detail area Y of FIG. 4.

DETAILED DESCRIPTION

A preferred embodiment container 10 of the present invention in the openand closed arrangement is shown in FIGS. 1 and 2. In practical use, theouter surface of floor 31 of base 25 will normally rest upon a surface(such as a table top) considered horizontal in reference to the user.Thus, the directional terms “vertical” and “horizontal” and the like areused to describe the container 10 and its components with respect to theorientation illustrated in FIG. 2 and are employed merely for thepurposes of clarity and illustration. For example, in the orientationshown in FIG. 2, lid 11 of closed container 10 is spaced “vertically”from the base 25. The directional terms “inner,” “outer,” and the likeare used herein with respect to the described container to refer todirections along the directional component toward and away from thegeometric center of the container.

Container 10 is preferably thermoformed. As shown by the figures,container 10 is composed of lid 11 and base 25. Lid 11 includes topsurface 12, descending surface (sidewall) 19 and multi-segment rim 14.Lid 11 and base 25 are manufactured from a conventional plasticmaterial. Lid 11 is preferably clear. Top surface 12 may include levelsor features of varying height, but is preferably flat. It may also becontoured and have ribs 16 in accordance with the prior art to enhancesuch factors as container volume, strength, nesting of multiple lids,stackability of closed containers and see-through visibility. In thepreferred embodiment, lid top surface 12 includes top plateau 15.Sidewall 19 extends from top surface 12 to horizontal segment 17 and mayinclude ribs 13 for strength. Horizontal segment 17 extends fromsidewall 19 to vertical inner wall 18. Sidewall 19 preferably includesribs 7 for strength and, in the depicted preferred embodiment,represents an outermost side surface of the lid.

The structure of preferred embodiment lid rim 14 will now be discussedin further detail. As best shown in FIG. 10, lid rim 14 includesperipherally projecting segment 20, which extends between inner wall 18and outer wall 21, creating channel 23. The cross-section profile ofsegment 20 is generally horizontal. The profile, however, can be shapedto include structure such as ribbing, curves or bends to modulate rimrigidity or flexibility so as to enhance the closing, sealing andopening functions of the rim as needed. The drawings depict a preferredembodiment cross-section profile of this peripherally projectingsegment. As viewed in FIG. 10 outer wall 21 extends downwardly betweenperipherally projecting segment 20 and peripheral flange 22. Outer wall21 is preferably angled to frictionally engage projection 35 furtherdescribed below.

The structure of preferred embodiment rim structure 30 of base 25 isbest shown in FIG. 11. Base 25 includes a bottom-most level or floor 31adjoined to sidewall 32. Sidewall 32 extends between base floor 31 andmulti-segment rim 30. Sidewall 32 preferably includes ribs 41 forstrength. The structure of base rim 30 is adapted to complementarilyengage the structure of lid rim 14 when lid 11 and base 25 are placed insealing arrangement. In this respect, the lower portion of base rim 30includes sidewall-to-rim transition segment 33. Transition segment 33flares outwardly from the top of sidewall 32 and curves upwardly intobase shelf 34. Base shelf 34 extends outwardly from base 25 and curvesupwardly to form sealing projection 35. Preferred embodiment container10 has at least two sealing projections 35. As viewed in FIG. 11,sealing projection 35 comprises outer vertical segment 36 and innerascending segment 37. Top sealing segment 38 spans between segments 36,37. Peripheral flange 42 extends outwardly from segment 36.

As shown in FIG. 9, projections 35 are located at spaced apart intervalson shelf 34 so as to create base rim gaps 39 between two adjacentprojections. Each base rim gap 39 is preferably located so as togeometrically oppose a counterpart base rim gap 39 located on thecontainer. For example, in the disclosed embodiment square containerdepicted in FIG. 1, base rim gaps 39 are disposed in opposingrelationship on each pair of parallel container sides. Lid rim structure14 preferably contains similar projections 26 located on horizontalsegment 17. Projections 26 are complementarily located on rim structure14 such that they align with and frictionally contact projections 35when lid 11 is closed to base 25. Projections 26 serve to buttressprojections 35 and keep lid 11 from twisting about base 25. Lid rim gaps27 are disposed between projections 26 on lid rim 14. In addition, byfrictionally engaging projections 35, projections 26 make the engagementbetween lid 11 and base 25 stronger. As shown in the drawings, theheight of projections 35 emanating from the base rim structure preventslid flange 22 from sealing completely against base flange 42. As aresult, when the lid is fully engaged to the base, projections 35 ofbase rim 30 are engaged by channel 23 and projections 26 of lid rim 14.However, the height of engaged projections 35 is such that flange 22 andflange 42 do not meet when the lid is engaged by the base. In thisregard, when the container is closed, one or more lid rim gaps 27between projections 26 of the lid align both vertically and horizontallywith a base rim gap 39 of the base rim. Hence, base rim gaps 39 betweenthe base rim projections are now roofed by rim 14 and create at leasttwo rim intake ports 40 that allow air to directly enter the containergenerally horizontally.

In carrying out the invention it is not important which rim, lid orbase, is provided with the projections 35 or the engaging channel 23.Accordingly, in another embodiment, base rim 30 could be provided withchannel 23 and lid rim 14 could be provided with projections 35. Infact, other rim engaging methods could be used as long as the sealingrim structures of the lid and base create intake ports 40 when the rimsare in sealing arrangement.

When the lid rim and base rim are in sealing arrangement, the containercomprises at least one set of counterpart intake ports 40 (a firstintake port and a first counterpart intake port). More specifically, inthe present invention container, the lid rim and base rim when in closedengagement form at least one first intake port disposed between the tworims. In addition, it is a feature of the invention that each firstintake port has at least one first counterpart intake port disposedbetween the two rims. In contrast to prior art containers, the intakeports of the present invention allow air to flow directly through therims of the container and not travel a serpentine course through rimstructure. In addition, in comparison to prior art containers, theintake ports of the present invention allow air to flow directly intothe container in a generally horizontal manner without having to travelan angled path. Hence, in the present invention intake ports 40 are notangled toward the container top.

The at least one first intake port and its one or more first counterpartintake ports are disposed between the two rims such as to permit air toenter the container through an intake port, cross at least a portion ofthe interior of the container under the food contents and then, as itwarms, rise and exit the container through the exhaust vents in the topsurface of the lid. For balanced moisture removal, each first intakeport 40 is located in the engaged rims 14, 30 and has at least one firstcounterpart intake port 40 similarly located in the engaged rims 14, 30.In the shown preferred embodiment container, each first intake port 40is located on the closed container such that it geometrically opposes(is perpendicularly across from) one counterpart intake port 40 on theother side of the container. This arrangement enables the cross-flow ofair underneath food contents throughout the entire container in the caseof a pressure differential between the ends of the one or more channels.The invention thus allows drier air to flow into the container throughan intake port 40, under the container contents and out through theexhaust vents 28 in the top surface of the lid. Though the depictedembodiment container shows an intake port 40 to have only onecounterpart intake port 40, an intake port 40 may have more than onecounterpart intake port 40.

Floor 31 includes two or more ribs 50 and may have alternating levels orelevations for strength and fluid control. To further enhance foodcrispness, floor 31 of base 25 comprises ribs 50 in floor recess 51.Floor recess 51 is a preferred embodiment feature. Ribs 50 projectupward from floor recess 51. Spaced apart elongated ribs 50 are alignedwith the line defined by at least one set of counterpart intake ports 40and form at least one channel 55. The one or more channels 55 act asflow paths for the relatively drier air inducted into the containerthrough intake ports 40. In this regard, the formation of alignedchannels 55 on floor 31 differs from the prior art container with floorbottoms provided with grids, wells or other structural features intendedto capture and retain liquid. These structural floor elements, thoughuseful in preventing sloshing of liquids or keeping food raised abovepooled liquids serve as barriers to air flow underneath the container'sfood contents.

In the depicted preferred embodiment the one or more channels 55 arelengthwise centered along one dimension of the floor and extendsubstantially across the length of the floor. Further, recess 51 isformed in floor 31 so as to guide incoming air to the channels and allowincoming air to fan (branch) out to the multiple of channels disposed init. The at least one channel 55 is oriented such that it extends in thedirection of one set of counterpart intake ports 40 and thus the sidesof the channel act like interior baffles. In the disclosed embodiment,the container depicts six channels 55 aligned with intake ports 40disposed on the ends of the container. By virtue of being oriented inthis fashion, channel 55 allows steam gases that may form from pooledliquid to rise and be conveyed away from food contents by convection,thus reducing the over-moistening of the bottom of food. Additionally,by virtue of the intake ports 40, drier air may flow into intake ports40 and around and under the container contents. Specifically, by virtueof the baffle effect of channel 55, drier air entering into thecontainer through an intake port 40 may flow under food contents andexit out through top surface exhaust vents 28. In an alternativeembodiment, floor 31 could comprise a plurality of channels 55, at leasttwo of which are aligned in two different directions so as to providechannels that align with more than one set of counterpart intake ports40. Additionally, in the preferred embodiment, floor 31 includestextured surface platforms 52. Platforms 52 are embossed (raised) abovethe interior surface of floor 31 (and thus substantially higher than thesurface of recess 51). By virtue of this arrangement, food contents arelifted off the surface of floor 31 and the drier air entering thecontainer from the intake ports 40 can more easily flow under the foodcontents and into the one or more channels 55.

The terms “opposing,” “opposed” or “opposite” as used herein to describethe location of the base rim gaps 39 or intake ports 40 means that thegaps or portals are oriented to allow the flow of ventilation into thecontainer through one port, through a certain length or width of theinterior of the container and then toward at least one other intakeport. Hence, in the depicted rectangular container embodiment, a firstintake port 40 is situated on one side of the container and acounterpart intake port 40 is located across the container on theopposing parallel side of the container. In this case, the at least oneother counterpart intake port 40 would be preferably, but notnecessarily, located perpendicularly across from the first intake port40. Similarly, with a round container, the set of counterpart intakeports 40 would be preferably, but not necessarily, diametrically acrossfrom each other. Variations in the locations of counterpart ports 40(and gaps 39) and the alignment of the floor ribs 50 and channel 55 maybe made such that air only flows through a portion of the container andnot its entire width or length. For example, in a rectangular containerthe intake ports 40 could be located on adjacent sides of the containerto promote the diagonal flow of cross ventilation. The cross flow ofventilation in such an embodiment would be enhanced by having one ormore diagonally oriented floor channels 55 aligned with the intakeports. Additionally, each intake port 40 preferably has at least onecounterpart intake port 40 to achieve cross flow ventilation. Thus, anintake port 40 could have more than one counterpart intake port 40.

As shown in FIG. 2 to further enhance the convection flow in thecontainer, the lid of the preferred embodiment container includes aplurality of exhaust vents 28 disposed about the top surface 12 of thecontainer lid. For optimum convection movement in the container, it iscritical that exhaust vents 28 be disposed and arranged on the topsurface 12 of the container and not on any of the outermost sidesurfaces of the lid. Otherwise, the inductive action on intake ports 40is lessened or the inducted air may not have an opportunity to drop tothe container floor before being pushed out by convection forces. At thesame time, to enhance convective movement inside the container it ispreferable that the plurality of exhaust vents 28 on the top surface 12of the lid be disposed away from the lid center so that they follow thecontour (as viewed from overhead) of the lid shape. In the depictedembodiment shown in FIG. 2, an exemplary number and arrangement ofsurface exhaust vents is shown on an approximately 9″×8″ rectangularcontainer. Tests on this exemplary embodiment show that the optimumconvection movement in the container occurs with a plurality of 14exhaust vents disposed in the shown pattern about the periphery of thetop surface of the lid and located within the range of 1″ to 1¼″(measured from the front edge of the vent) from the nearest outer edgeof the top surface of the container. For most food service applications(side dish sized containers to entrée sized containers) a plurality ofat least 8 top surface exhaust vents 28 works well, with the range of 8to 14 vents (cruciate slit type) showing optimum results. As shown inFIG. 2, it is further preferable that exhaust vents 28 be disposed sothat they direct rising gases and vapors outward in relation to thecontainer's outermost exterior side surfaces. This arrangement ofexhaust vents on the lid top surface and the absence of vents on theoutermost side surfaces of the lid removes the dead-air effect caused byhaving apertures on the side of the lid in close proximity to(particularly above) the rim vents. By removing this dead-air effect,convection in the container is enhanced.

A container constructed in accordance with the present invention can bemanufactured in a variety of shapes and sizes, and is preferably formedof resins or plastic materials including, but not limited to,polyethylene, polypropylene, polyvinyl chloride or polyethyleneterephthalate (“PET”). The container lid and base can be transparent ortranslucent, and may be colored in either instance. The size and numberof intake and exhaust vents can be varied to accommodate the foodheating environment or the requirements of the food placed in thecontainer. The container can be made by a variety of processes includingthermoforming, vacuum forming,, blow molding, extrusion molding orinjection molding. Further, the container can be of any shape, includinground or polygonal. The lid and base of the container may be separatearticles or may include the depicted hinge such that the lid and baseare connected to each other in a clamshell configuration.

Having described the invention in detail, those skilled in the art willappreciate that modifications may be made of the invention withoutdeparting from its spirit. Therefore, it is not intended that the scopeof the invention be limited to the specific embodiment illustrated anddescribed.

1. A plastic food container comprising: a lid and a base; the lid andbase each having a peripheral rim; the lid rim adapted for closingengagement with the base rim; the lid rim and base rim when in closedengagement forming an interior of the container, a first intake portdisposed between the two rims and a first counterpart intake portdisposed between the two rims; the first intake port and the firstcounterpart intake port being further disposed between the two engagedrims such as to permit air to enter directly and generally horizontallyinto the container; the first intake port and the first counterpartintake port defining a line in the interior of the container thatextends from the first intake port to the first counterpart intake port;the base comprising a floor, the floor having at least one channelformed therein that is aligned with the line defined by the first intakeport and the first counterpart intake port; the lid including a topsurface and one or more outermost side surfaces, the one or moreoutermost side surfaces having no vents disposed on them; and the topsurface of the lid having a plurality of exhaust vents disposed on it.2. The container of claim 1 wherein the plurality of exhaust ventsdisposed on the top surface of the container lid numbers between eightand fourteen vents.
 3. The container of claim 1 wherein the lid includesa contour and the plurality of exhaust vents on the top surface of thelid are disposed on the lid top surface so that they follow the contourof the lid shape.
 4. The container of claim 1 wherein the exhaust ventsdisposed on the top surface of the lid are formed so that they directrising gases and vapors outward in relation to the outermost sidesurfaces of the lid.
 5. The food container of claim 1 wherein the lidrim and base rim when in closed engagement form a second intake portdisposed between the two rims and a second counterpart intake portdisposed between the two rims; and the second intake port and the secondcounterpart intake port are disposed between the two engaged rims suchas to permit air to enter directly and generally horizontally into thecontainer.
 6. The container of claim 5 wherein the second intake portand the second counterpart intake port define a second line in theinterior of the container that extends from the second intake port tothe second counterpart intake port and the floor has a second channelformed therein that is aligned with the second line.
 7. The container ofclaim 1 wherein the peripheral rim of the lid comprises at least twosealing projections, the peripheral rim of the base has a channel andwhen the lid and base are in the closed arrangement the at least twosealing projections of the lid rim are engaged by the channel in theperipheral rim of the base.
 8. The container of claim 1 wherein the lidis hinged to the base.